Argentine President Cristina Fernandez de Kirchner delivers a speech in front of a backdrop displaying the Falkland Islands (Malvinas in Spanish) painted like the Argentine national flag at Government Palace in Buenos Aires on February 7, 2012.

Argentina said today five British companies were illegally exploring for oil off the Falklands, Bloomberg reported.

The activities of Rockhopper Exploration, Desire Petroleum Public Limited Company, Argos Resources, Falkland Oil and Gas Limited and Borders & Southern Petroleum were “illegal and clandestine” and cleared the way for legal action, the government said, according to the Buenos Aires Herald.

The companies "are not authorized by the Argentine government under law," Agence France-Presse reported, citing a resolution published in Argentina's Official Bulletin by Energy Secretary Daniel Cameron.

Three decades after Argentina’s invasion of the island triggered the Falklands War, which ended in humiliating defeat for Buenos Aires and caused the deaths of 649 Argentine and 255 British servicemen, tensions between the two countries remain high.

Rising crude oil prices and dwindling reserves in the North Sea have lured British companies to the Falklands, located 8,000 miles (12,900 kilometers) from Britain.